Variable ratio transmission



March 7, 1939. v o` E. szEKELY 2,149,320

VARIABLE RATIO TRANSMISS ION March 7, 1939. o. E. szEKELY VARIABLE RATIO TRANSMISSION Filed May l, 1937 5 Sheets-Sheet 2 rfa E S25/(4 Y www@ March 7, 1939. o E. szl-:KELY- VARIABLE RATIO TRANSMISSION Filed May l, 1937 5` Sheets-Sheet 5 ll/lll lea' gmc/who@ Orr@ E592 .eA/.64V

marisa Mu. 1, 1939? PATENT OFFICE VARIABLE RATIO TRANSMISSION Otto E. Slekeiy,.Elmira, N. Y., assimor to The gzoely Company, Inc., a corporation of New Application my 1, im, sei-nu No. 140,229

` 13 claims. (c1. 'I4-29a) This invention relates to improvements in variable ratiotransmissions and is concerned with mechanisms by which torque increment effects may be attained under automatic control by the l load demand.

One of the features of the present invention is the provision of a structure by which plural ranges of torque ratio transmission may be effected, with inversely corresponding speed ratios,

'10 with the employment of a manual ,control for torque transfers throughv the structure.

Other features of the invention reside in the construction and arrangement of parts, as will appear more fully hereinafter.

Illustrative forms of practicing theA invention artica-lift out on the accompanying drawings, in w Fig. 1 is a longitudinal upright sectional view Y through a transmission assembly.

Figs. 2, 3, 4 and 5 are corresponding transverse o sectionalviews, respectively taken substantially on the lines 2 2, 3 3, 4 4, and 5 5 of Fig.` 1. Figs. 6, 7, 8 and 9 are fragmentary detail views showing modifications in the construction.

In these drawings, the transmission mechanism is intended for transferring power from a shaft Ill, which is coupled to any suitable prime mover (not shown), to a nal driven or tail shaft which is coupled to the load to be driven, so that the load placesv a torque demand'upon this 'is shown as having a fly wheel I2 associated with a clutch structure I3 for driving a shaft |4. This shaft is keyed or otherwise secured to a differential case I5l which is freely rotatable on the antifriction bearings I6 mounted in a front housing member Ha.

The differential case I5 has the inwardly extending pivot pinsv I1 which receive the planet pinions I3, The gear I9 is xed on a shaft 20,

Athis shaft being supported for rotation by. the

shaft The drivingfor prime mover shaft I0 anti-friction bearings 2| disposed between it and the differential case, by the plain sleeve bearings 22, and by a further anti-friction bearing 23 at 5 its rear end. The shaft 20 is keyed or otherwise secured to the central gear 24 of an epicyclic 5 train. The second gear 30 in the differential case I5 is provided with a hollow shaft extension 3| which surrounds the shaft 20 and engages the plain bearings 22, and is supported thereby and also is mounted by the anti-friction bearing 32 10 for easy rotation in the differential case I5. The hollow. shaft 3| is connected to the central gear 33 of a fluid displacement pump.

'Ihis fluid displacement pump includes the housing 34 located between the flanges 35, 36. 15 The flange 35 has a peripheral channel groove 31 in its front face, for cooperation with a similar groove 31a provided in the end member Hb of the central housing portion Hc. Within the pump housing 34 are the pump pinions 38 which 20 are mounted to turn about axes which travel with the pump housing assembly while the pinions 38 remain in mesh with the central pump gear 33. Fluid delivered from the pump passes through discharge channels 39 to a peripheral groove 40 25 formed in the hub of the right-hand flange 36, and thence to a corresponding groove in the web wall Hca of the housing member Hc, and thus gains access to a conduit 4| formed in this wall,

and finally passes back by the conduit 42 into '30 the sump 43 provided by the lower portion of the housing structure. Flow through the conduits 4|, 42 may be regulated by a valve 44.

Keyedto the right-hand flange 36 of the pump structure is a -member 50 provided with internally 35 cut gear teeth 5|. The member 50 is ixedly connected to a dished plate structure 52 which has a sleeve 53 onto which is fxedly secured a core 54 of an overrunning clutch assembly, as will be described in greater detail hereinafter. The plate 40 5 3 has an anti-friction bearing 55 located between itself and the shaft Planet pinions of an epicyclic set are in mesh 'both with the gear teeth 5| and with the teeth of gear 24, and are carried by pivots con- 45 nected to the carrier spider 6| located at one face of the gears 24, 60, in association with a spider portion 62 located at the other face thereof and connected by the bolts 52a and spacing collars B2b. The carrier spider 6| is secured to or 50 formed integral with the final driven shaft and is in supporting relation with the shaft 20 by the aforesaid anti-friction bearing 23.

The tail or nal driven shaft is mounted by anti-friction bearings 66 on the end member Hd 55 and a duct 82 with this sump space.

of the general housing. This end member also has an inwardly extending flange Hda to receivey the hardened outer sleeve member 61 of the over- The several parts of the housing are .secured iixedly together so that it operates to retain a liquid therein. This liquid is usually an oil which is effective without change Vof' physical condition clutch, and hence at maximum and minimum temperatures of service.

The manner of operation of the structure is as follows:

When the prime mover is at a standstill, all

parts of the transmission are likewise at a stand- 1 still, and it may be assumed that the valve 44 is open. v

The clutch I3 may be opened -and the prime mover set in motion. `This permits the usual operations of starting the prime moverif it is a gasoline engine or other device which exerts only a low torque during the starting condition or when moving atvery low speed.

When the prime mover-has attained Va Vdesired speed, the clutch I3 may be closed. For the purpose of a simple explanation ofthe operation of the device, it will be assumed that at,` this instant the prime mover begins to deliver a'conn stant torque at a particular speed: and that this torque and speed of the prime mover shaft I will be maintained during the operations of bringing the nal driven shaft II to .the same speed.

When the clutch I3 has been closed, the shaft lI4 turns at the same speed as the shaft III. Thus,

the differential case I5 4is likewise drivenat this same speed, and the planet pinion pins I1 are carried in rotation about the common axis at this same speed. The overrunning clutch rollers 1lir prevent the gear 30 from turning faster than the shaft 20, and thus overcome the tendency of the gear 30 to be turned at twice the `speed of the differential case I5, while the gear I9 is held fast by reason of load resistance. Hence,ithe differential case I5, and the ,gear and planet pinion means` providing the first differential gearing, turn as a unit: and the inner pump gear v"33 and the small gear 24 of the epicyclic or second differentiating gearing are likewise turned therewith: all of theseparts are therefore revolving at the speed ofthe `prime move The small gear 24 produces a pressure upon the planet pinions 60 tending to turn these about their axes.' 'I'his results in a relatively backward pressure exerted by'the planet vpinions 60 upon the gear teeth 5I.

being exerted upon the gear teeth 5I tending-to force them ina counterclockwise directiomalong with the associated structures 5 0, 52 and the pump housing. This retrograde movement of these parts, however, is prevented by the engagement of the there is no retrograde rotation relative to thev frame. Hence, the planet pinions 60 roll on the gear teeth 5I which are stationary, and the spider 6I, 62 is carried along with the gear 24, and turnsl in a clockwise direction for rollers 68of the overrunning driving the tail shaft -II. The speed ratio between the shafts I0, I4 and 20 (and gear 24) with respect to the tail shaft I I may then be expressed by the formula:

in which E represents the effective diameter of the gear 24, and R represents the effective diameter of the gear teeth 5I. Thus, if gears'24 and 60 are of thev same effective diameter, then gear teeth 5I have an effective diameter `three times as great: and Athen the above equation indicates that the rotational speed of the tail shaft II is'one-fourth of the rotational speed of the prime mover and of the shaft 20.

The torque ratio may b similarly computed, bytheformula:

' T E-i-R orque at tail shaft=Eng1ne torqueX E and hence the torque at the tail shaft, with the stated relation of the gears 24, 5I, is four times the torque delivered at the prime mover. It will be noted that the power and energy conditions remain the same, as these are represented by forin the system. The speed of the tail shaft varies directly with the speed of the engine, and hence the actuation of the load is functionally'related directly .to the prime mover characteristics of speed and torque. It will be noted, therefore, that this mechanical drive provides for initially accelerating a load, andfor the delivery of greatly, increased torque effects; and is available for propelling a vehicle, for example, even in the event of disruption in the hydraulic system. It may, advantageously, be used under the aforesaidcondition of constant speed and torque at' the engine, in propelling an automobile up a steep grade. v H

If such a vehicle then passesv upon a lesser grade, the operatormay move the valve 44 to- .ward closed condition. Back pressure effects' are thus set .up at thegear pump. When these pressure effects exceed, for example, the pressure eiects existing in therst differential and tending therein to rotate the gear 30 faster than the shaft 20, a condition corresponding to a variablemiddle ratio is attained The inner pump gear 33 is retardedV by this back pressure in the gear pump, so that it turns slower than the shaft 2Il, andltherewith the gear 30 turns slower than the diierential case I5. This occasions a rotation'of the planet pinionsIB about their respective axes I1, and therewith causes an increase of the rotaf tional speed of the gear I9^with .respect to the Y differential case, so that the shaft 20 now turns faster than the diierential case. As before, the 'shaft 20 rotates the' gear 24 in the second diii'erentiating gearing. The pressures existing in the gear pump arenot suiilcient to overcome the reaction pressuresbetween pinions and gear teeth 5I as applied through the clutch rollers 68 back pressure eifect in the gear pump may be regarded as retarding the inner pump gear 93 until it is substantially stationary with respect to the pump housing. At this time, the gear 30 is substantially stationary. In the form shown .in Fig. 1, the two lgears 30I9 are of the same .effective diameter; and hence, under these conditions, the gear I9 is rotated at twice the speed of the diil'erential case I5. Since the shaft 20 isY now turning at twice the speed, the 4.: 1. speed reduction in the second gearing now brings the tail shaft I I to a speed which is one-half of the speed of the prime mover. Correspondingly, the torque delivered to the tail shaft II is'twice the torque delivered at the prime mover. Again,'the relation of the speed and torque show that the prime lmover is continuing to deliver energy at the same constant rate as stated above.

Under these conditions, it will be noted that action and reaction are present in lthe gear pump,

by reason of the back pressure upon the liquid: so l that essentially half of the torque is being delivered from the pump housing, through the members 50, 52, to-the clutch rollers 68 and thence to the frame, but this torque component has no corresponding speed component, as the parts are at a standstill, and hence no Apower transfer (save obviousmechanical and hydraulic losses) is oc y curring in this control portion of the system.

It will be noted that this change from a condition of 4:1 torque ratio and a 1:4 speed ratio, existing at the low speed is determined by the setting of the valve 44, so long as the torque demand on the tail shaft II remains constant. Conversely, for a given valve setting, variations in the torque demand upon the tail shaft I I (as in passing from a steep hill to one of lesser grade) will result in the passage'of, the system tothe aforesaid condition at which the torque ratio is,

say, 2: 1 and the speed ratio is 1:2. l

If the road passes from the moderate rupgrade to a level condition so that the torque demand drops still lower, then the reaction pressure in the gear pump becomes greater than the reaction pressure between the planet pinions 60 and gear teeth 5I as applied to the frame through the clutch rollersv 68. The pump housing structure now remains locked or blocked, so that its parts turn at substantially the same speed. The system passes to this condition by starting a slow forward rotation of the pump housing and theref with of the members 50, 52, and the overrunning clutch rollers 68 now permit this forward movement of the parts. 'I'his condition continues with acceleration of the pump housing and the members 50, 52, until these parts are turning at prime mover speed; with further, decrease of the torque ratio, and increase of the speed ratio, during the transition phase; until alll parts are turning together and at prime mover speed. This represents a direct drive or 1:1 speed ratio and 1:1

mover is delivering a greater torque than is demanded byy the load at this 1:1 ratio, theprime mover speeds up, in accordance with its own characteristics, until the torque and speed at the Aprime mover `exactly correspond to the torque demand of the load at the identical speed. On the other hand, if the load increases, the ultimate Vresult is a passage from the 1:1 ratio successively to the 2:1 torque ratio and then (if demanded Vby the load) to the 4:1 torque ratio, along with corresponding decreases of speed, if the prime mover torque andspeed remain constant. If the prime mover torque and speed change, it is obvious that similar but not necessarily linearly-corresponding changes occur atV the load.

In the above'description, the dierential member I5 has been referred to as a case: and the epicyclic member 6l, 62 has been .referredto as a spider. These terms are interchangeable: and have been employed for simplicity of description --and claiming. Thus, the differentiating gearings each include three relatively movable members herein illustrated as comprising two gears on a common axis, these gears being in mesh with planet pinion means carried by the `case lor spider. The two beveled gears I9, 30 in Figure 1 and the corresponding gears I9a, 30a andvl9b, 30D in Figures 6 and 7 are sometimes called sun gears:

while the gear 24 in Figure 1 and gears 3Ilc, Id

rratio of the gear 24 to gear teeth 5I may be adr justed to attain the desired torque and speed relationship. It is also possible to control such a relationship by having the gears I9, 30 of the first dierentiating gearing of properly selected different effective diameters. Thus, in Fig. 6, the dierential case I5a supports the planet pinions I8a, which are in mesh with a large gear I9a and a small gear 30a. In this form, the large gear I9a is fixed to the shaft'20; while the gear 30 is connected to the inner pump gear 33. In this structure, the gear I9a is not driven at twice the speed of the differential case I 5a. when the gear 30a is held at a standstill with the pump assembly, and hence a greater multiplication of torque occurs in the system, for a given relationship of the gear 24 and gear teeth 5I.

An inverse condition is shown diagrammatically in Figl 7, where the planet pinions I8b on the case I5b are in mesh with sun gears I9b and 30h, but with the gear I 9b smaller than the gear 30h. In this case, the torque multiplication is less, with the same assumed relative sizes of parts in the second differentiating gearing.

It is likewise possible to construct the first differentiating gearing of strictly epicyclic type, as shown by Figs. 8 and 9.

In the form of Fig. 8, the differential case It'vcY supports the planet pinions |81:v which are located in the same plane and are in mesh with the small gear 30e and the large, internally cut gear I9c. This arrangement of parts corresponds to that of Fig, 6, in producing a greater torque multipllcation.

In the form of Fig. 9, the differential case I5d carries the planet pinions I8d which are in mesh with the large gear 30d and the small gear I9d.

The relative sizes of the coaxial gears in the first differential gearing are selected according to the requirements of the system. Thus the forms of Figs. 6 and 8 are advantageous for heavy duty vehicles such as trucks, wherea slow acceleration from 1:4 to a 1:2 and then to a 1:1

speed ratio is permissible. With lighter vehicles,

such as fast passenger automobiles, the forms of tageous as it provides three compartments in a housing structure, these compartments receiving,

in order from. the front end, the first differential geari g, the fluid displacement pump structures,

and t e second diiferentiating gearing: and permit the employment of closely spaced bearings which are illustrated as of anti-friction type, for permitting the easy movement of the parts in respect to one another and the housing, at points where the parts perform relative movements during conditions of heavy load demand.

. This is a hydraulically-controlled mechanicallydriven transmission in which maximum loads to be moved respective to the various established gearratios, actuated through and by a mechanical drive and the hydraulic end is used for the transfer of speed-torque ratios from one to the other. Y

The transmission can be employed for many purposes in driving stationary machinery and vehicles., It has particular advantages in association with prime movers having a torque characteristic representing a very low torque output at starting and at low speeds, and hence can be employed in automobile service with variable speed enginesas well as with prime movers having a substantially constant speed, during running, with varying torque output.

In the illustrated form, the invention has been shown as arranged for a prime mover of low torque characteristic at low speeds, such as an internal combustion engine. For such uses, it is advantageous-to have the clutch I 3 actuatable, and this is accomplished in any usual manner; for example, by engagement of the usualclutch fork (not shown) in the clutch groove I3a. It is obvious that the invention is not limited solely tothe forms of construction illustrated, but that itmay be employed in many ways within the scope of the appended claims.

I claim: l

1. A variable ratio transmission comprising a frame, a driving member, a driven member; rst and second differentiating gearlngs' each comprising rst and second gears having a common axis, a planet pinion' and a differential member revoluble with the planet pinion about the common axis, theA said nrst gears in each differentiating gearing being connected together, and uidl pressure means including two relatively movable parts respectively connected to* the said second gears and effective for retarding the relative angular motion of said second gears; one said differential member being connected to the driving member and the other said differential member being connected to the driven member.

2. A variable ratio transmission comprising a frame, a` driving member, a driven member; a first diierential gearing having apair of coaxial gears, a differential case and a planet pinion, said differential case being connected to the driving member; a second differential gearing having a pair of coaxial gears, a spider and planet pinion ential gearing from turning backward relative accelerations be- K to the said other gear in one dinerential gearing and the other said part being connected to the said other gear in the other differential gearing; and means for establishing a variable back pressure in said gear pump.

3. A variable ratio transmission as in claim 2,

I in which said back pressure establishing means includes conduit means for liquid circulation through the gear pump, and avalve in said conduit means for limiting the liquid delivery from said pump.

4. A variable ratio transmission comprising a frame, a driving member, a driven member; first and second dierentiating gearings each comprising rst and second gears having a common axis, a planet pinion and a differential member revoiuble with the planet pinion about the common axis, the first gears in each ldifferentiating gearing being connected together, and fluid pressure means including' two relatively movable parts respectively connected to the said second gears and eiIective for retarding the relative angular motion of said second gears; one said differential member being connected to the driving member and the corresponding gears being of the same size, the other said differential memand second differentiating gearings eacl. .com-

prising rst and second gears having a common axis, a planet pinion and a differential member revoiuble with the planet pinion about the common axis, the first gears in each differentiating gearing being connected together, both said differentiating gearings .having their gears of different sizes, the large first gear inthe first differential being connected to the small first gear in the second differential, and fluid pressure means including two relatively movable parts respectively connected to the second gears and effective for retarding therelative angular motion of said second gears; the differential member of said first differentiating gearing being connected to the driving member and the differential member of the second differentiating gearing being connected to the driven member.

6; A variable ratio transmission vcomprising a frame, a driving member, a driven member; rst and second differentiating gearings each comprising rst and second gears having a common axis, a planet pinion and a differential member revoiuble with the planet pinion about the common axis, the rst gears in each differentiating gearing being connected together, each difierentiating gearing having its gears of different sizes, the smaliiirst gears of the two gearings being connected together, and iluid pressure means including two relatively movable parts respectivelyv connected to the large second gears and effective for retarding the relative angular motion of said second gears; one said differential member being connected to the driving member and the other said differential member being connected to the driven member. 7. A variable ratio transmission comprising housing, a driving member, a driven member; a first differential including first and second gears, a diierentialcase, and a planet pinion journalled on the differential case; a iiuid displacement pump including a pump housing, an inner pump gear, and a pump pinion journalled in the pump housing in mesh with ythe pump gear; a second differential including large` and small gears, a

s,14o,sao

spider and a planet pinion iournalled on the spider in mesh with said large and small gears; a ilrst overrunning clutch effective between said rst and` second gears for preventing said second gear from turning faster than said first gear, a second overrunning clutch eiecti've between said large gear and the frame for preventing said large gear from turning backward relative to the frame; and means for controlling the ilow oi' uid through said pump so that the back pressure thereat may be varied; said driving member being connected to said dinerential cas'e, said ilrst gear Abeing connected to said small gear, said second gear being connected to said pump gear, saidv l5 pmnp housing being connected to said large gear.

said spider 'being connected to the driven member.

8. A variable ratio transmission including a frame, a driving member, a driven member: a first diilerentiating gearing connected to the driving member; .means for limiting the relative movement of parts of said mst gearing; a second -parts oi' said diierentiating gearings, and dediiierentiating gearing connectedr to the driven member and including gears of dierent sizes and planet pinions-in mesh therewith; means mechanically connecting parts of said diiIeren-'4 tiating gearings 1`in driving relation; further means including brake devices connecting other vices4 for controlling the braking eilfect; and means for limiting the movement of said other parts in said second gearing` relative to the frame.

9. A variable ratio transmission including a v frame, a driving member, a. driven member; a

nrst differentiating gearing including tlrst and second gears, a planet pinion in mesh therewith, and a differential case supporting the planet pinion and connected to the driving member; means for limiting the relative movement of said gears in the first gearing; a second diiierentiate ing gearing including small and large gears. a planet pinion in meshgwith said small andV large gears, and a diiierential spider supporting the latter planet pinion and connected to the driven member; said iirst and small gears being condriving relation with the driven member; means connecting another said element in each gearing together; and brake means including a iirst part connected to a further element in one of said gearings and a second part connected to a further element in the other of said gearings for controlling the relative movements thereof whereby to determine the ratio of power transi'er through said connecting means from the 'driving to the driven member.

11. A transmission as in' claim 10, and including means in one of said gearings for limiting diii'erential movements oi said elements thereof when actuated in one direction.

12. A ton as in claim 10, including means for restraining an element of one of said gearings against retrograde movement ,relative to the trame. t

13. A transmission as in claim 10, in which one of said gearings includes a member for preventing one gear from overrunning the other gear, and said other gearing includes means for restraining an element thereof against retrograde movement relative to the frame.

OTIO E. SZEKELY. 

